The natural history of streptococcal skin infection: prevention with topical antibiotics.

An investigation on the natural history of streptococcal skin infection was done in fifty-nine children in a rural day care setting. A double-blind study for prevention of streptococcal pyoderma was done during the peak season for skin infection. Triple antibiotic ointment, containing bacitracin, polysporin, and neomycin, was compared to placebo ointment. Ointments were applied thrice daily for minor skin trauma; mosquito bites and abrasions were predominant. Cultures of normal skin surfaces were taken for group A streptococci each week of the 15-week study period. Skin lesions were cultured whenever present. Eighty-one percent of the fifty-nine patients had positive normal skin cultures on one or more occasions. Nineteen children (32%) developed streptococcal pyoderma. Infection occurred significantly more often in children using placebo ointment than in those using topical antibiotic (47% vs 15%; p = 0.01). The infecting strain was first recovered from normal skin surfaces in 67% of placebo patients and in two of the four patients using antibiotic ointment. This study further confirms the importance of skin carriage of group A streptococci as a precursor to pyoderma and demonstrates the importance of minor skin trauma as a predisposing factor. Topical antibiotics may be useful in preventing streptococcal pyoderma, especially in children known to be at increased risk for such infection.